Android软件框架的搭建_笔记总录
一、接触到的两种布局
RelativeLayout 绝对布局
LinearLayout 线性布局
目前还未可以说出对这两种布局的感受
但要说出一点的话，就是在这个框架的
搭建中，启动页面的布局中嵌套一个图
标，或者嵌套一个线性布局，这样方便
部分内容居中(基于整个父屏幕)
二、设置进度条显示的颜色【ProgressBar】
5.0 后 Material Design 支持快速修改progressBar颜色
<ProgressBar android:id="@+id/pg" style="@style/WrapWrap" android:layout_centerInParent="true" android:indeterminateTintMode="src_atop" android:indeterminateTint="@color/colorPrimary"/>
关键在于修改以下两句代码
android:indeterminateTintMode="src_atop"
android:indeterminateTint="@color/colorPrimary"
三、启动场景中触击屏幕加载程序主场景_疑难解答
/*当用户触击屏幕后，启动主场景*/ @Override public boolean onTouchEvent(MotionEvent event) { Log.e(TAG,"主场景被第 "+event.getAction()+" 次发射启动"); /*发射*/ launcherMainActivity(); return super.onTouchEvent(event); }
用户触击屏幕，导致Activity被启动多次
原因是因为在启动场景Activity的Java类中的onCreate方法中，
创建了一个Handler对象，在启动场景加载了2秒后，也调用了一次定义好的启动程序主场景的函数
所以按照代码的顺序，启动了3次Activity
其中的2次，是触击屏幕的时候，触击的一次，离开屏幕的一次
解决方法1
在程序配置清单文件中，设置程序的主场景Activity为单例模式
<activity android:name=".MainActivity" android:launchMode="singleTask"/>
关键在于加入以下的配置参数
android:launchMode="singleTask"
这其实还隐含了一个Bug，当用户触击屏幕进入主场景后，立即点击了返回键/桌面键，这个时候又去到了onCreate方法中
执行了onCreate函数，又再次启动了一次程序主场景
解决方法
使用定义全局的Handler对象，调用onDestroy函数，
使用onDestroy函数中调用全局Handler对象的removeCallbacksAndMessages移除Handler对象
private Handler splashHandler = new Handler(); @Override protected void onDestroy() { super.onDestroy(); splashHandler.removeCallbacksAndMessages(null); }
解决方法2【可选，学会一种就很牛逼了】
从源头上控制
取消MainActivity的单例模式
不设置 android:launchMode=“singleTask”
取消以上这个设置
设置一个布尔类型的全局属性
/*定义isLaunch属性，判断是否已经启动*/ private boolean isLaunchMain = false;
判断是否已经启动，取反让程序执行一次
当进入后，就设置为true
下次再进去那就条件不成立了
那就也是实现了同样的效果
private void launcherMainActivity() { if(!isLaunchMain) { /*进入后就设置为true，下次if判断条件不成立就不会再次执行到这里*/ isLaunchMain = true; /*创建启动主场景的意图对象*/ Intent mainPageIntent = new Intent(this, MainActivity.class); /*启动*/ startActivity(mainPageIntent); /*关闭当前场景*/ finish(); } }
四、沉浸式状态栏的实现
自从Android 5.0发行后，沉浸式状态栏笋干兴起，笋干爆炸。
实现步骤：
android系统5.0之前是不可修改状态栏的背景色的，为了兼容之前的版本，需要创建三个资源文件
<!-- 沉浸式的实现 --> <!--在Android 4.4之前的版本上运行，直接跟随系统主题--> <style name="TranslucentTheme" parent="AppTheme" />
<?xml version="1.0" encoding="utf-8"?> <resources> <style name="TranslucentTheme" parent="Theme.AppCompat.Light.NoActionBar"> //设置为true，意味着xml布局延伸到状态栏 <item name="android:windowTranslucentStatus">true</item> <item name="android:windowTranslucentNavigation">false</item> </style> </resources>
<?xml version="1.0" encoding="utf-8"?> <resources> <style name="TranslucentTheme" parent="Theme.AppCompat.Light.NoActionBar"> <!--//设置为false，意味着布局不会延伸到状态栏--> <item name="android:windowTranslucentStatus">false</item> <item name="android:windowTranslucentNavigation">false</item> <!--Android 5.x开始需要把颜色设置为程序的主题色白色，否则导航栏会呈现系统默认的浅灰色--> <item name="android:statusBarColor">@android:color/white</item> </style> </resources>
创建BaseImmersive类
package com.ljf.atguigu.ui; import android.annotation.TargetApi; import android.app.Activity; import android.graphics.Color; import android.os.Build; import android.view.View; import android.view.Window; import android.view.WindowManager; import java.lang.reflect.Field; public class BaseImmersive { private Activity activity; public BaseImmersive (Activity content){ this.activity = content; } /** * 设置状态栏背景颜色 * * 遇到的问题：7.0（含）以上的系统，状态栏修改为透明色无效 * * 解决办法：在Activity的onCreate方法中，调用setContentView()之前需调用以下方法 */ public void statusBarColor() { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) { try { Class decorViewClazz = Class.forName("com.android.internal.policy.DecorView"); Field field = decorViewClazz.getDeclaredField("mSemiTransparentStatusBarColor"); field.setAccessible(true); field.setInt(activity.getWindow().getDecorView(), Color.TRANSPARENT); //改为透明 } catch (Exception e) { } } } /** * 设置字体和图标颜色 * * 修改状态栏中的文字及图标的颜色--android系统6.0以上可修改 * * 在Activity的onCreate方法中加入代码 */ public void setStatusBarTextAndIconsColor() { /*状态栏中的文字颜色和图标颜色，需要android系统6.0以上，而且目前只有一种可以修改（一种是深色，一种是浅色即白色）*/ if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) { /*修改为深色，因为我们把状态栏的背景色修改为主题色白色，默认的文字及图标颜色为白色，导致看不到了。*/ activity.getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR); } } /** * 设置背景颜色和标题栏背景颜色一致 */ public void setStatusBarColorIsTitleBarColor(int colorCode) { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) { setTranslucentStatus(true); SystemBarTintManager tintManager = new SystemBarTintManager(activity); tintManager.setStatusBarTintEnabled(true); tintManager.setStatusBarTintResource(colorCode);//状态栏所需颜色 } } /** * 兼容API版本19 * @param on */ @TargetApi(19) private void setTranslucentStatus(boolean on) { Window win = activity.getWindow(); WindowManager.LayoutParams winParams = win.getAttributes(); final int bits = WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS; if (on) { winParams.flags |= bits; } else { winParams.flags &= ~bits; } win.setAttributes(winParams); } }
实现效果 ：
但程序主场景设置了引用了标题栏布局资源，背景色是单独的，所以，为了兼容SDK API版本
需要一个系统的功能类插件
创建 SystemBarTintManager类，这是系统的。
复制代码到工程中
package com.ljf.atguigu.ui; import android.annotation.SuppressLint; import android.annotation.TargetApi; import android.app.Activity; import android.content.Context; import android.content.res.Configuration; import android.content.res.Resources; import android.content.res.TypedArray; import android.graphics.drawable.Drawable; import android.os.Build; import android.util.DisplayMetrics; import android.util.TypedValue; import android.view.Gravity; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewGroup; import android.view.Window; import android.view.WindowManager; import android.widget.FrameLayout.LayoutParams; import java.lang.reflect.Method; /** * Class to manage status and navigation bar tint effects when using KitKat * translucent system UI modes. */ @SuppressWarnings({"rawtypes", "unchecked"}) public class SystemBarTintManager { static { // Android allows a system property to override the presence of the navigation bar. // Used by the emulator. // See https://github.com/android/platform_frameworks_base/blob/master/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java#L1076 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) { try { Class c = Class.forName("android.os.SystemProperties"); Method m = c.getDeclaredMethod("get", String.class); m.setAccessible(true); sNavBarOverride = (String) m.invoke(null, "qemu.hw.mainkeys"); } catch (Throwable e) { sNavBarOverride = null; } } } /** * The default system bar tint color value. */ public static final int DEFAULT_TINT_COLOR = 0x99000000; private static String sNavBarOverride; private final SystemBarConfig mConfig; private boolean mStatusBarAvailable; private boolean mNavBarAvailable; private boolean mStatusBarTintEnabled; private boolean mNavBarTintEnabled; private View mStatusBarTintView; private View mNavBarTintView; /** * Constructor. Call this in the host activity onCreate method after its * content view has been set. You should always create new instances when * the host activity is recreated. * * @param activity The host activity. */ @TargetApi(19) public SystemBarTintManager(Activity activity) { Window win = activity.getWindow(); ViewGroup decorViewGroup = (ViewGroup) win.getDecorView(); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) { // check theme attrs int[] attrs = {android.R.attr.windowTranslucentStatus, android.R.attr.windowTranslucentNavigation}; TypedArray a = activity.obtainStyledAttributes(attrs); try { mStatusBarAvailable = a.getBoolean(0, false); mNavBarAvailable = a.getBoolean(1, false); } finally { a.recycle(); } // check window flags WindowManager.LayoutParams winParams = win.getAttributes(); int bits = WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS; if ((winParams.flags & bits) != 0) { mStatusBarAvailable = true; } bits = WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION; if ((winParams.flags & bits) != 0) { mNavBarAvailable = true; } } mConfig = new SystemBarConfig(activity, mStatusBarAvailable, mNavBarAvailable); // device might not have virtual navigation keys if (!mConfig.hasNavigtionBar()) { mNavBarAvailable = false; } if (mStatusBarAvailable) { setupStatusBarView(activity, decorViewGroup); } if (mNavBarAvailable) { setupNavBarView(activity, decorViewGroup); } } /** * Enable tinting of the system status bar. * <p/> * If the platform is running Jelly Bean or earlier, or translucent system * UI modes have not been enabled in either the theme or via window flags, * then this method does nothing. * * @param enabled True to enable tinting, false to disable it (default). */ public void setStatusBarTintEnabled(boolean enabled) { mStatusBarTintEnabled = enabled; if (mStatusBarAvailable) { mStatusBarTintView.setVisibility(enabled ? View.VISIBLE : View.GONE); } } /** * Enable tinting of the system navigation bar. * <p/> * If the platform does not have soft navigation keys, is running Jelly Bean * or earlier, or translucent system UI modes have not been enabled in either * the theme or via window flags, then this method does nothing. * * @param enabled True to enable tinting, false to disable it (default). */ public void setNavigationBarTintEnabled(boolean enabled) { mNavBarTintEnabled = enabled; if (mNavBarAvailable) { mNavBarTintView.setVisibility(enabled ? View.VISIBLE : View.GONE); } } /** * Apply the specified color tint to all system UI bars. * * @param color The color of the background tint. */ public void setTintColor(int color) { setStatusBarTintColor(color); setNavigationBarTintColor(color); } /** * Apply the specified drawable or color resource to all system UI bars. * * @param res The identifier of the resource. */ public void setTintResource(int res) { setStatusBarTintResource(res); setNavigationBarTintResource(res); } /** * Apply the specified drawable to all system UI bars. * * @param drawable The drawable to use as the background, or null to remove it. */ public void setTintDrawable(Drawable drawable) { setStatusBarTintDrawable(drawable); setNavigationBarTintDrawable(drawable); } /** * Apply the specified alpha to all system UI bars. * * @param alpha The alpha to use */ public void setTintAlpha(float alpha) { setStatusBarAlpha(alpha); setNavigationBarAlpha(alpha); } /** * Apply the specified color tint to the system status bar. * * @param color The color of the background tint. */ public void setStatusBarTintColor(int color) { if (mStatusBarAvailable) { mStatusBarTintView.setBackgroundColor(color); } } /** * Apply the specified drawable or color resource to the system status bar. * * @param res The identifier of the resource. */ public void setStatusBarTintResource(int res) { if (mStatusBarAvailable) { mStatusBarTintView.setBackgroundResource(res); } } /** * Apply the specified drawable to the system status bar. * * @param drawable The drawable to use as the background, or null to remove it. */ @SuppressWarnings("deprecation") public void setStatusBarTintDrawable(Drawable drawable) { if (mStatusBarAvailable) { mStatusBarTintView.setBackgroundDrawable(drawable); } } /** * Apply the specified alpha to the system status bar. * * @param alpha The alpha to use */ @TargetApi(11) public void setStatusBarAlpha(float alpha) { if (mStatusBarAvailable && Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { mStatusBarTintView.setAlpha(alpha); } } /** * Apply the specified color tint to the system navigation bar. * * @param color The color of the background tint. */ public void setNavigationBarTintColor(int color) { if (mNavBarAvailable) { mNavBarTintView.setBackgroundColor(color); } } /** * Apply the specified drawable or color resource to the system navigation bar. * * @param res The identifier of the resource. */ public void setNavigationBarTintResource(int res) { if (mNavBarAvailable) { mNavBarTintView.setBackgroundResource(res); } } /** * Apply the specified drawable to the system navigation bar. * * @param drawable The drawable to use as the background, or null to remove it. */ @SuppressWarnings("deprecation") public void setNavigationBarTintDrawable(Drawable drawable) { if (mNavBarAvailable) { mNavBarTintView.setBackgroundDrawable(drawable); } } /** * Apply the specified alpha to the system navigation bar. * * @param alpha The alpha to use */ @TargetApi(11) public void setNavigationBarAlpha(float alpha) { if (mNavBarAvailable && Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { mNavBarTintView.setAlpha(alpha); } } /** * Get the system bar configuration. * * @return The system bar configuration for the current device configuration. */ public SystemBarConfig getConfig() { return mConfig; } /** * Is tinting enabled for the system status bar? * * @return True if enabled, False otherwise. */ public boolean isStatusBarTintEnabled() { return mStatusBarTintEnabled; } /** * Is tinting enabled for the system navigation bar? * * @return True if enabled, False otherwise. */ public boolean isNavBarTintEnabled() { return mNavBarTintEnabled; } private void setupStatusBarView(Context context, ViewGroup decorViewGroup) { mStatusBarTintView = new View(context); LayoutParams params = new LayoutParams(LayoutParams.MATCH_PARENT, mConfig.getStatusBarHeight()); params.gravity = Gravity.TOP; if (mNavBarAvailable && !mConfig.isNavigationAtBottom()) { params.rightMargin = mConfig.getNavigationBarWidth(); } mStatusBarTintView.setLayoutParams(params); mStatusBarTintView.setBackgroundColor(DEFAULT_TINT_COLOR); mStatusBarTintView.setVisibility(View.GONE); decorViewGroup.addView(mStatusBarTintView); } private void setupNavBarView(Context context, ViewGroup decorViewGroup) { mNavBarTintView = new View(context); LayoutParams params; if (mConfig.isNavigationAtBottom()) { params = new LayoutParams(LayoutParams.MATCH_PARENT, mConfig.getNavigationBarHeight()); params.gravity = Gravity.BOTTOM; } else { params = new LayoutParams(mConfig.getNavigationBarWidth(), LayoutParams.MATCH_PARENT); params.gravity = Gravity.RIGHT; } mNavBarTintView.setLayoutParams(params); mNavBarTintView.setBackgroundColor(DEFAULT_TINT_COLOR); mNavBarTintView.setVisibility(View.GONE); decorViewGroup.addView(mNavBarTintView); } /** * Class which describes system bar sizing and other characteristics for the current * device configuration. */ public static class SystemBarConfig { private static final String STATUS_BAR_HEIGHT_RES_NAME = "status_bar_height"; private static final String NAV_BAR_HEIGHT_RES_NAME = "navigation_bar_height"; private static final String NAV_BAR_HEIGHT_LANDSCAPE_RES_NAME = "navigation_bar_height_landscape"; private static final String NAV_BAR_WIDTH_RES_NAME = "navigation_bar_width"; private static final String SHOW_NAV_BAR_RES_NAME = "config_showNavigationBar"; private final boolean mTranslucentStatusBar; private final boolean mTranslucentNavBar; private final int mStatusBarHeight; private final int mActionBarHeight; private final boolean mHasNavigationBar; private final int mNavigationBarHeight; private final int mNavigationBarWidth; private final boolean mInPortrait; private final float mSmallestWidthDp; private SystemBarConfig(Activity activity, boolean translucentStatusBar, boolean traslucentNavBar) { Resources res = activity.getResources(); mInPortrait = (res.getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT); mSmallestWidthDp = getSmallestWidthDp(activity); mStatusBarHeight = getInternalDimensionSize(res, STATUS_BAR_HEIGHT_RES_NAME); mActionBarHeight = getActionBarHeight(activity); mNavigationBarHeight = getNavigationBarHeight(activity); mNavigationBarWidth = getNavigationBarWidth(activity); mHasNavigationBar = (mNavigationBarHeight > 0); mTranslucentStatusBar = translucentStatusBar; mTranslucentNavBar = traslucentNavBar; } @TargetApi(14) private int getActionBarHeight(Context context) { int result = 0; if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) { TypedValue tv = new TypedValue(); context.getTheme().resolveAttribute(android.R.attr.actionBarSize, tv, true); result = TypedValue.complexToDimensionPixelSize(tv.data, context.getResources().getDisplayMetrics()); } return result; } @TargetApi(14) private int getNavigationBarHeight(Context context) { Resources res = context.getResources(); int result = 0; if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) { if (hasNavBar(context)) { String key; if (mInPortrait) { key = NAV_BAR_HEIGHT_RES_NAME; } else { key = NAV_BAR_HEIGHT_LANDSCAPE_RES_NAME; } return getInternalDimensionSize(res, key); } } return result; } @TargetApi(14) private int getNavigationBarWidth(Context context) { Resources res = context.getResources(); int result = 0; if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) { if (hasNavBar(context)) { return getInternalDimensionSize(res, NAV_BAR_WIDTH_RES_NAME); } } return result; } @TargetApi(14) private boolean hasNavBar(Context context) { Resources res = context.getResources(); int resourceId = res.getIdentifier(SHOW_NAV_BAR_RES_NAME, "bool", "android"); if (resourceId != 0) { boolean hasNav = res.getBoolean(resourceId); // check override flag (see static block) if ("1".equals(sNavBarOverride)) { hasNav = false; } else if ("0".equals(sNavBarOverride)) { hasNav = true; } return hasNav; } else { // fallback return !ViewConfiguration.get(context).hasPermanentMenuKey(); } } private int getInternalDimensionSize(Resources res, String key) { int result = 0; int resourceId = res.getIdentifier(key, "dimen", "android"); if (resourceId > 0) { result = res.getDimensionPixelSize(resourceId); } return result; } @SuppressLint("NewApi") private float getSmallestWidthDp(Activity activity) { DisplayMetrics metrics = new DisplayMetrics(); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) { activity.getWindowManager().getDefaultDisplay().getRealMetrics(metrics); } else { // TODO this is not correct, but we don't really care pre-kitkat activity.getWindowManager().getDefaultDisplay().getMetrics(metrics); } float widthDp = metrics.widthPixels / metrics.density; float heightDp = metrics.heightPixels / metrics.density; return Math.min(widthDp, heightDp); } /** * Should a navigation bar appear at the bottom of the screen in the current * device configuration? A navigation bar may appear on the right side of * the screen in certain configurations. * * @return True if navigation should appear at the bottom of the screen, False otherwise. */ public boolean isNavigationAtBottom() { return (mSmallestWidthDp >= 600 || mInPortrait); } /** * Get the height of the system status bar. * * @return The height of the status bar (in pixels). */ public int getStatusBarHeight() { return mStatusBarHeight; } /** * Get the height of the action bar. * * @return The height of the action bar (in pixels). */ public int getActionBarHeight() { return mActionBarHeight; } /** * Does this device have a system navigation bar? * * @return True if this device uses soft key navigation, False otherwise. */ public boolean hasNavigtionBar() { return mHasNavigationBar; } /** * Get the height of the system navigation bar. * * @return The height of the navigation bar (in pixels). If the device does not have * soft navigation keys, this will always return 0. */ public int getNavigationBarHeight() { return mNavigationBarHeight; } /** * Get the width of the system navigation bar when it is placed vertically on the screen. * * @return The nbsp;width of the navigation bar (in pixels). If the device does not have * soft navigation keys, this will always return 0. */ public int getNavigationBarWidth() { return mNavigationBarWidth; } /** * Get the layout inset for any system UI that appears at the top of the screen. * * @param withActionBar True to include the height of the action bar, False otherwise. * @return The layout inset (in pixels). */ public int getPixelInsetTop(boolean withActionBar) { return (mTranslucentStatusBar ? mStatusBarHeight : 0) + (withActionBar ? mActionBarHeight : 0); } /** * Get the layout inset for any system UI that appears at the bottom of the screen. * * @return The layout inset (in pixels). */ public int getPixelInsetBottom() { if (mTranslucentNavBar && isNavigationAtBottom()) { return mNavigationBarHeight; } else { return 0; } } /** * Get the layout inset for any system UI that appears at the right of the screen. * * @return The layout inset (in pixels). */ public int getPixelInsetRight() { if (mTranslucentNavBar && !isNavigationAtBottom()) { return mNavigationBarWidth; } else { return 0; } } } }
/*在键值对资源中，定义mainPageStatusBarColor*/
<color name="mainPageStatusBarColor">@android:color/holo_blue_light</color>
调用函数
baseImmersive.setStatusBarColorIsTitleBarColor(R.color.mainPageStatusBarColor);
因为布局的原因，重叠了，代码设置
在布局资源的根节点
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" android:fitsSystemWindows="true">
关键设置
android:fitsSystemWindows="true"
这样，就大功告成了。
接下来，开始实现布局
大致记录最关键的
五、框架的实现_重点笔记
· 主页面底部按钮RadioGroup -> RadioButton
虽然设置了那个安卓原生的按钮，效果为NULL
android:button="null"
当按下按钮，还是会有一层触击效果的，这是安卓原生自带
解决方法
设置background的值为NULL
就搞定了，【注意，当把这些可重复利用的样式放到键值对资源后，需要给null值加上@符号，否则程序会报异常】
android:background="null"
设置好，就可以看到，按钮按下就不会有那层圆圈形状的效果层出现
· 处理横竖屏切换导致页面被再次初始化的问题
在程序清单文件中，设置改变时不再次初始化帧布局子页面
<activity android:name=".MainActivity" android:configChanges="orientation|keyboard|screenSize"/>
关键为以下这句配置
core -> android:configChanges="orientation|keyboard|screenSize"
@orientation 屏幕方向
@keyboard 键盘弹出收起
@screenSize 屏幕大小改变
· 处理已经显示过的场景再次被切换并再次被初始化的问题
代码
/*记录备切换掉的Fragment 全局属性 */ private Fragment mContent; private void switchFragment(Fragment from,Fragment to) { /*开启一个帧布局场景管理者的事务*/ FragmentTransaction ft = getSupportFragmentManager().beginTransaction(); /*如果两者不是同一个*/ if(from != to){ mContent = to;/*记录被切换到的*/ /*才切换*/ /*判断to是否被添加 第一次返回的是false，把它作为条件取反，让条件成立， 再次来到这，就是true取反，就不会被再次创建*/ if(!to.isAdded()){ /* 首次from、to可能是空指针，需要判空 */ /*隐藏from*/ if(from != null) ft.hide(from); /*添加to*/ if(to != null) ft.add(R.id.fl_main_content,to).commit(); }else { /* 首次from、to可能是空指针，需要判空 */ /*已经被添加*/ /*隐藏from*/ if(from != null) ft.hide(from); /*显示to*/ if(to != null) ft.show(to).commit(); } } }
六、使用 ListView 来呈现常用框架的名称
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